zic

Synopsis

Description

zic reads text from the file(s) named on the command line and
creates the time conversion information files specified in this input. If a
filename is '-', the standard input is read.

Input lines are made up of fields. Fields are separated by any
number of white space characters. Leading and trailing white space on input
lines is ignored. A pound sign (#) indicates a comment that extends
to the end of the line. White space characters and pound signs can
be enclosed within double quotes (" ") if they are to be used
as part of a field. Any line that is blank (after comment
stripping) is ignored. Non-blank lines are expected to be of one of
three types: rule lines, zone lines, or link lines.

Rule

A rule line has the form:

For example:

Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S

The fields that make up a rule line are:

Rule USA 1969 1973 - Apr lastSun 2:00 1:00 D

NAME

Gives the (arbitrary) name of the set of rules this rule is part of.

FROM

Gives the first year in which the rule applies. The word minimum (or an abbreviation) means the minimum year with a representable time value. The word maximum (or an abbreviation) means the maximum year with a representable time value.

TO

Gives the final year in which the rule applies. In addition to minimum and maximum (as above), the word only (or an abbreviation) can be used to repeat the value of the FROM field.

TYPE

Gives the type of year in which the rule applies. If TYPE is:

'-'

The rule applies in all years between FROM and TO, inclusive.

uspres

The rule applies in U.S. Presidential election years.

nonpres

The rule applies in years other than U.S. Presidential election years.

even

The rule applies to even-numbered years.

odd

The rule applies to odd-numbered years.

If TYPE is something else, then zic will attempt to execute the command

yearistypeyeartype

to check the type of a year: an exit status of 0 means that the year is of the given type; an exit status of 1 means that the year is not of the given type. The yearistype command is not currently provided in the Solaris environment.

IN

Names the month in which the rule takes effect. Month names can be abbreviated.

ON

Gives the day on which the rule takes effect. Recognized forms include:

5

the fifth day of the month

lastSun

The last Sunday in the month

lastMon

The last Monday in the month

Sun>=8

First Sunday on or after the eighth

Sun<=25

Last Sunday on or before the 25th

Names of days of the week can be abbreviated or spelled out in full. Note: There cannot be spaces within the ON field.

AT

Gives the time of day at which the rule takes effect. Recognized forms include:

2

Time in hours

2:00

Time in hours and minutes

15:00

24-hour format time (for times after noon)

1:28:14

Time in hours, minutes, and seconds, where hour 0 is midnight at the start of the day and hour 24 is midnight at the end of the day.

Any of these forms can be followed by the letter w if the given time is local “wall clock” time; s if the given time is local “standard” time; or u (or g or z) if the given time is universal time. In the absence of an indicator, wall clock time is assumed.

SAVE

Gives the amount of time to be added to local standard time when the rule is in effect. This field has the same format as the AT field (without the w and s suffixes).

LETTER/S

Gives the “variable part” (for example, the “S” or “D” in “EST” or “EDT” of time zone abbreviations to be used when this rule is in effect. If this field is '-', the variable part is null.

Zone

A zone line has the form:

Zone NAME GMTOFF RULES/SAVE FORMAT [UNTIL]

For example:

Zone Australia/SouthWest 9:30 - CST 1992 Mar 15 12:00
8:30 Aus CST

The fields that make up a zone line are:

NAME

The name of the time zone. This is the name used in creating the time conversion information file for the zone.

GMTOFF

The amount of time to add to UTC to get standard time in this zone. This field has the same format as the AT and SAVE fields of rule lines; begin the field with a minus sign to subtract time from UTC.

RULES/SAVE

The name of the rule(s) that apply in the time zone or, alternately, an amount of time to add to local standard time. If this field is `-', then standard time always applies in the time zone.

FORMAT

The format for time zone abbreviations in this time zone. The pair of characters %s is used to show where the “variable part” of the time zone abbreviation goes. Alternately, a slash (/) separates standard and daylight abbreviations.

UNTIL

The time at which the UTC offset or the rule(s) change for a location. It is specified as a year, a month, a day, and a time of day. The time of day has the same format as the AT field of rule lines. If this is specified, the time zone information is generated from the given UTC offset and rule change until the time specified.

The month, day, and time of day have the same format as the IN, ON, and AT columns of a rule; trailing columns can be omitted, and default to the earliest possible value for the missing columns.

The next line must be a “continuation” line. This line has the same form as a zone line except that the string “Zone” and the name are omitted. The continuation line places information starting at the time specified as the UNTIL field in the previous line in the file used by the previous line. Continuation lines can contain an UNTIL field, just as zone lines do, indicating that the next line is a further continuation.

Link

A link line has the form:

Link LINK-FROM LINK-TO

For example:

Link Europe/Istanbul Asia/Istanbul

The LINK-FROM field should appear as the NAME field in some zone
line; the LINK-TO field is used as an alternate name for that
zone.

Except for continuation lines, lines can appear in any order in the
input.

Options

--version

Outputs version information and exits.

-ddirectory

Creates time conversion information files in the directory directory rather than in the standard directory /usr/share/lib/zoneinfo.

-llocaltime

Uses the given time zone as local time localtime. zic acts as if the file contained a link line of the form:

Link localtime localtime

-pposixrules

Uses the rules of the given time zone posixrules when handling POSIX-format time zone environment variables. zic acts as if the input contained a link line of the form:

Limits time values stored in output files to values that are the same whether they are taken to be signed or unsigned. You can use this option to generate SVVS-compatible files.

This option is obsolete and may be removed in a future release.

-v

Complains if a year that appears in a data file is outside the range of years representable by system time values (0:00:00 a.m.UTC,January 1, 1970, to 3:14:07 a.m.UTC,January 19, 2038). This option also complains if a time of 24:00 (which cannot be handled by pre-1998 versions of zic) appears in the input.

-yyearistype

Uses the given command yearistype rather than yearistype when checking year types (see Rules under DESCRIPTION).

Operands

filename

A file containing input lines that specify the time conversion information files to be created. If a filename is '-', the standard input is read.

See Also

Notes

For areas with more than two types of local time, you might
need to use local standard time in the AT field of the
earliest transition time's rule to ensure that the earliest transition time recorded
in the compiled file is correct.

If the current timezone file is edited and compiled using the “zic”
command, the changes will only be reflected in any new processes that
are running. The most accurate way to reflect the changes for
the whole system would be a reboot.